SCARIDAE Parrotfishes by D.R

click for previous page 3468 Bony Fishes SCARIDAE Parrotfishes by D.R. Bellwood iagnostic characters: Body oblong, moderately compressed (size to 120 cm). Head generally bluntly Drounded anteriorly. Jaws at most only slightly protrusible; teeth usually fused to form a pair of beak-like plates in each jaw, but a few species (Calotomus) have free, imbricate, incisor-like teeth present externally in upper and lower jaws. Small, isolated, projecting teeth (canines) occur in some species on outer sides of upper jaw; pharyngeal dentition strong consisting of interdigitating paired upper pharyngeals with rows of elongate molariform teeth on a slightly or strongly convex surface; these teeth bear against the elongate molariform teeth on the surface of the single lower pharyngeal bone. Dorsal fin continuous, with IX slender, flexible spines and 10 soft rays; anal fin with III flexible spines and 9 soft rays; pectoral fins with 2 unbranched rays (the first always rudimentary, the second supporting most of the leading margin of the fin), and 11 to 14 branched rays, caudal fin varying from rounded to lunate, with produced caudal-fin lobes, the shape often changing with growth. Scales large, cycloid, 22 to 24 on lateral line; fins without scales, except for a basal row on the median fins of most species; 1 to 4 rows of scales on cheek; 2 to 8 median predorsal scales. Colour: most species very colourful; many exhibit striking sexual dichromatism. Most species have 2 distinct adult colour phases (although a few appear to be monochromatic as adults). The relationship between colour phase and sex is complex, most species are protogynous hermaphrodites (individuals maturing first as females, then sexually transforming into males). This sexual transformation is usually accompanied by a change in colour phase. This basic pattern is further complicated, in some species, by the presence of primary males (i.e. non-sex changing individuals) which may also change colour phase as they grow. In species where 2 adult colour phases are known, the first is termed “initial phase” (IP), the second, “terminal phase” (TP). Initial phases may thus be male or female, while terminal phases are invariably male. Initial phase fish are rather drably coloured, with browns and greys usually predominating. Colour patterns of terminal phase fish are complex, with predominantly green, blue, and pink hues. For field identification of parrotfish species, reliance must usually be placed on colour patterns, as few meristic characters are of value. No key to species is given here. As an aid for the identification of species occurring in the area, colour plates are included in this volume. 2-8 median single dorsal fin with IX flexible spines predorsal scales and 10 soft rays teeth usually fused to form dental plates 1 2 3 cheek scales in 1-4 rows anal fin with III spines (“cheek-scale rows”) and 9 soft rays large cycloid scales Habitat, biology, and fisheries: Parrotfishes are most often found on or in the vicinity of coral reefs, and are usually most abundant in shallow waters to a depth of 30 m. They feed principally on algae and associated material scraped from rocks or dead corals. Ingested material is ground in the pharyngeal mill which reduces it to a fine slurry. Some species move over large areas, while others are strongly site attached and vulnerable to overfishing. Parrotfishes are not a major commercial catch, but they may form a significant component of artisanal fisheries and are frequently found in fish markets. Although they are highly popular food fishes in some areas, no catch data on parrotfishes are currently reported to FAO. They are usually caught in traps, gill nets, or by spearing. Their flesh is relatively soft and does not keep well, and parrotfishes are therefore marketed and eaten fresh. Perciformes: Labroidei: Scaridae 3469 Remarks: The species of Scaridae have been widely confused in the taxonomic literature and records from the area are often unreliable. The distributions given below rely largely on more recent literature and area records probably underestimate distributions. Similar families occurring in the area The beak-like plates of most Scaridae, in addition to features such as large smooth scales and often bright colours, usually preclude parrotfishes being confused with any other fish family. However, members of the genus Calotomus, in which the teeth are not fused (Fig. 1), might be confused with some Labridae (wrasses), but in the latter family the teeth are usually well separated in the jaws and the mouth is clearly protrusible. Occasionally, species of another labrid genus, Choerodon, may be mistaken for a scarid. example of labrid dentition Identification note In the species accounts below, the number of “scales in cheek-scale rows” (see family figure on previous page) is presented as short formulas in which the first numeral indicates the respective scale row on the cheek (counted from above), with the number of scales in this row given in parenthesis, e.g. “2(3-6)” [= “second scale row with 3 to 6 scales” ]. Key to the genera of Scaridae occurring in the area Parrotfishes are difficult to identify. There are few morphological features or meristic values that enable even genera to be separated. At the species level, meristic values are rarely diagnostic. Most identifications therefore must rely on colour patterns. However, most species have at least 3 distinct patterns throughout life (juvenile, IP, and TP). The colours also change after death. Many species share common colour patterns especially as IPs. The WCP area also contains a lot of geographic variants or species pairs which overlap, particularly in the western part of the area. Accurate identifications for many species is best restricted to the colourful TP stage. The following key provides some assistance in identifying genera. Species are best identified using the colour plates at the end of this volume. 1a. One row of scales below eye (Figs 1 and 2); pectoral-fin rays 13 (rarely 12 or 14) ........® 2 1b. Two or more rows of scales below eye (Figs 4 to 8); pectoral-fin rays 14 to 16 (rarely 13 or 17) .................................................® 3 2a. Teeth not fused, upper dental plates directly opposed (Fig. 1) . Calotomus 2b. Teeth fused to form narrow dental plate, upper dental plate enclosed within lower dental plates when jaws closed (Fig. 2) . Leptoscarus teeth not teeth fused fused 1 scale row 1 scale row Fig. 1 Calotomus Fig. 2 Leptoscarus 3a. Individual teeth on dental plates clearly visible (Fig. 3a, b), cement covering the dental plates restricted to base and invariably white, no lateral canine teeth; posterior nostril large (more than twice size of anterior nostril; Figs 4 and 5) ....................® 4 3b. Dental plates covered with cement (Fig. 3c) coloured white, blue or blue-green, individual teeth only visible near biting edge, lateral canine teeth often present (Fig. 3b); posterior nostril small (usually of similar size to anterior nostril; Figs 6 to 8) ............® 5 3470 Bony Fishes nodules on each tooth dental lateral plates canine covered tooth in cement a) Bolbometopon b) Cetoscarus c) Hipposcarus, Chlorurus, Scarus Fig. 3 4a. Head profile steep with distinct hump, profile almost vertical in large individuals (more than 60 cm standard length; Fig. 4); outer face of each tooth with small nodule at base (in specimens more than 35 cm standard length; Fig. 3a); 1 row of scales on interopercle (Fig. 4); median predorsal scales 2 to 5 (usually 4); pectoral-fin rays 15 or 16 . Bolbometopon 4b. No hump present above eye, head profile evenly convex (Fig. 5); outer face of each tooth rounded with no tubercle (Fig. 3b); 2 rows of scales on interopercle (Fig. 5); median predorsal scales 5 to 7; pectoral-fin rays 14 (occasionally 15) . Cetoscarus hump enlarging hind nostril with age large hind nostril large 2 rows of scales on interopercle 1 row of scales on interopercle Fig. 4 Bolbometopon Fig. 5 Cetoscarus 5a. Head profile pointed with distinctly angular snout; eye near dorsal profile; dental plates hind nostril relatively narrow with white cement; cheek small scales small, in an isolated patch, in indis- tinct rows (body uniformly pale, caudal and caudal peduncle often with yellow hue) (Fig. 6) . Hipposcarus 5b. Head profile not pointed, snout blunt or narrow rounded; eye not near dorsal profile; dental dental plates relatively deep with white, blue or plates blue-green cement; cheek scales large, in 2 to 3 distinct rows, not in an isolated patch cheek scales (Figs 7 and 8); often dark or bright colours, small, in patch yellow caudal and uniformly pale body only Fig. 6 Hipposcarus in IP Scarus chameleon) ...............® 6 Perciformes: Labroidei: Scaridae 3471 6a. Dental plates broadly exposed (Fig. 7); cutting edge hind nostril dental small of jaws irregular, zig-zag su- plated tures joining lower jaw hind nostril covered (Fig. 9a); pectoral-fin rays 15 small by lips or more (exceptionally 14); broadly median predorsal scales 4 exposed dental (rarely 3) with no anterior plates pair; head profile blunt (bul- let-shaped or steep profile (Fig. 7) . Chlorurus 6b. Dental plates usually covered by lips (Fig. 8); cutting cheek scales edge of jaws usually even, cheek scales large straight sutures joining lower large jaw (Fig. 9b); pectoral-fin rays usually 15 or less; me- Fig. 7 Chlorurus Fig. 8 Scarus dian predorsal scales 3 to 8, usually 4 to 6, some species with an anterior pair; head profile rounded or angular (Fig. 8) . Scarus irregular cutting edge even cutting edge sutures straight sutures zig-zagged medial view lateral view medial view lateral view a) Chlorurus b) Scarus Fig. 9 lower jaw List of species occurring in the area The symbol 0 is given when species accounts are included.

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